1. Technical Field
The present disclosure relates to printed circuit boards, more particularly to a printed circuit board that can reduce electromagnetic interference.
2. Discussion of the Related Art
Printed circuit boards (PCBs) are widely used in electronic devices. When a PCB is used, electronic components of the PCB interfere with each other, thereby producing an interfering current called electromagnetic interference (EMI).
In order to prevent EMI, the interfering current needs to be electrically connected with a ground. A fixing member is passed through a through hole of the printed circuit board and engages with a housing that electrically connects with the ground. The printed circuit board includes a copper layer on a periphery of the through hole. A head portion of the fixing member contacts the copper layer. As such, the interfering current of the printed circuit board can be connected with the ground. However, the copper layer is easily oxidated. Thus, the copper layer needs to be coated by tin cream to prevent oxidation. In order to make the tin cream attach to the copper layer, the printed circuit board may be heated in an oven. In the oven, the tin cream is easily flowed into the through hole and fills the through hole. In order to prevent the tin cream from flowing in the through hole, the through hole is generally covered by adhesive tapes before the printed circuit board is placed into the oven.
However, it is very waste of time to mask the adhesive tapes, thereby causing high production costs.
Therefore, a new printed circuit board amending the aforementioned difficulties is desired.